Dialysate is typically continuously prepared by mixing a concentrated solution and water in apparatus containing a number of pumps, chambers, valves and flow restrictors in its hydraulic circuitry. It is often desirable to remove the source of concentrated solution and flush the hydraulic circuitry with water or treatment chemicals such as a cleanser or a bleach between uses, and it is desirable to have different treatment chemicals within the circuitry for different periods of time and pumped through it at different concentrations.